An outbreak of measles associated with an international dog show in Slovenia, November 2014.

In Slovenia, where measles virus had not been circulating for many years, an outbreak of measles among visitors of an international dog show occurred in November 2014. We identified 23 measles cases plus 21 presumable secondary and tertiary cases. Thirty-nine cases were adults, 27 to 56 years-old, 12 of them vaccinated with two doses. Five were unvac-cinated children. Thanks to high vaccination coverage (95.3% in birth cohort 2011) wider transmission is not expected in Slovenia. On 24 November 2014, the regional epidemiologist from Nova Gorica region notified the Communicable Diseases Centre of the National Institute of Public Health (NIJZ) about two suspected measles cases. Both had visited the international dog show in Vrtojba/ Šempeter, close to the Italian border, which took place on 8 and 9 November 2014. Dog owners from 27 (mostly European) countries participated. Around 1,100 persons were present at the exhibition (700 dog owners and ca 400 visitors). As this was the only link between the two cases, we assumed that they were infected there. In both cases, measles infection was laboratory-confirmed on the following two days by positive IgM and positive PCR. On 26 November, NIJZ alerted all primary physicians in the country about the event, to rapidly identify further cases. On the same afternoon, four more suspected cases were reported, and in the next two days, another nine that had all visited the exhibition. The measles case definition used in Slovenia is based on the case definitions of the European Union (EU) [1]. All suspected cases were laboratory-tested and measles was confirmed either by detecting measles-specific IgM antibodies in serum samples by ELISA (Serion Immundiagnostica, Würzburg, Germany) and/or by detecting measles antigen in a throat swab or urine with real-time RT-PCR [2]. In total, 28 suspected measles cases that visited the exhibition were tested for measles antigen and/or measles-specific IgM antibodies. In 18 cases, measles were confirmed according to laboratory criteria, and in five suspected cases measles was excluded. In the remaining five cases (three vaccinated with two doses and two with unknown vaccination status) with clinical presentation of measles, only extremely high IgG of > 5,000 mIU/ml was detected (cutoff for positivity: 200 mIU/ml). Although these five cases had negative IgM and negative PCR results, we considered that they, too, fulfilled the case definition and defined them as confirmed cases, which gives a total of 23 confirmed measles cases. In addition to the 23 …